DESCRIPTION (Applicant's Abstract): Delirium is a common, serious, and potentially preventable problem for hospitalized older patients, with occurrence rates of 25-60 percent, hospital mortality rates of 25-33 percent, and annual Medicare expenditures of over $4 billion (1994). Our previous study, the Delirium Prevention Trial, documented the effectiveness of a multi-component targeted intervention strategy for substantially reducing the risk of developing delirium during hospitalization, compared with usual care. The overall objectives of the current renewal application are to extend the analyses to examine cost-effectiveness, secondary and long-term outcomes, and effects of adherence on intervention effectiveness. These investigations will more fully establish the effectiveness of our intervention strategy, including its overall cost-effectiveness and the lasting nature of the benefits. The proposed study will involve the 852 subjects enrolled into the Delirium Prevention Trial, consisting of 426 matched pairs of intervention and usual care subjects. For the current proposal, we will supplement the data collected during the clinical trial, with one year of follow-up data from: 1) telephone interviews; 2) medical record reviews; 3) health care utilization and charge data from Medicare; 4) Connecticut Long-Term Care Registry; 5) hospital costs from the Hospital Information System; and 6) National Death Index. Using these data sources, cost-effectiveness ratios for the intervention vs. usual care groups will be estimated, using standard and multivariable approaches. The impact of the intervention on secondary and long-term outcomes (e.g., functional and cognitive status, depression, self-rated health, mortality, nursing home placement, and health care utilization) will be examined using standard and longitudinal repeated measures methods. Finally, the impact of adherence on intervention effectiveness will be estimated using bivariate and multivariable approaches. Strengths of the proposed project include the considerable progress and preliminary work, the innovative nature of the intervention strategy and of the analytic approaches in this matched clinical trial, the expertise and experience of the analytic team, and the supportive research environment. This study is highly significant for the promise it holds for demonstrating the effectiveness and cost-effectiveness of the Delirium Prevention Trial strategy, which may ultimately yield substantial health and quality of life benefits for the geriatric population at large.